With the rapid development of information technology, electrical document are widely used. For the purpose of storage, processing and delivery via internet network of the documents, it is necessary to scan the paper document into the format of electrical documents. However, to rapidly scan the document, there is a need to perform duplex scan (i.e. dual-side scanning) of the document.
FIG. 1 is a schematic block diagram of a conventional document scanner. The document scanner 100 only utilizes one charge coupled device (CCD) or one contact image sensor (CIS), and one analog front-end (AFE) unit. The document scanner 100 includes an image sensor 102, an analog front-end (AFE) unit 104, a scanning controller 106, and image memory 108. The scanning controller 106 further includes an image processor 110 and a timing generator 112. The image sensor 102 merely senses the image data in one-side of the paper document. The analog front-end (AFE) unit 104 converts the analog image data from the image sensor 102 into digital image data. The image processor 110 processes the digital image data and stores the processed digital image data in the image memory 108. The timing generator 112 controls the sensing timing of the image sensor 102 to generate the analog image data. Since the document scanner 100 only supports one analog front-end (AFE) unit and lack of dual CCDs or CISs, the document scanner 100 cannot perform duplex scanning.
FIG. 2 is a schematic block diagram of another conventional document scanner 200. The document scanner 200 only utilizes two charge coupled devices (CCDs) or two contact image sensors (CISs), and two analog front-end (AFE) units. The document scanner 200 includes two image sensors 202, two analog front-end (AFE) units 204, a scanning controller 206, and image memory 208. The scanning controller 206 further includes an image processor 210 and a timing generator 212. The front-side and back-side image sensors 202 sense the image data in the front-side and back-side of the paper document, respectively. The two analog front-end (AFE) units 204 convert the analog image data from the image sensors 202 into digital image data. The image processor 210 processes the digital image data and stores the processed digital image data in the image memory 208. The timing generator 212 controls the sensing timing of the image sensor 202 to generate the analog image data. Although the document scanner 200 supports dual-side scanning, however, two analog front-end (AFE) units need to be employed, thereby resulting in no cost-effectiveness. Moreover, the two analog front-end (AFE) units only output the digital image data sequentially and thus reduces the scanning speed of the document scanner 200. Consequently, there is a need to develop a novel scanner to solve the aforementioned problem.